Best approach to pass and handle arguments to function

Question

After some reading, I found myself struggling with two different approaches to pass a list of arguments to a function. I read some indications. That's what I figured out so far:

Actual code:

file caller.py:

import worker
worker.version_check(iserver,login,password,proxyUser,proxyPass,
  proxyServer,packageInfo)

worker.version_get(iserver,login,password,proxyUser,proxyPass,
  proxyServer,packageInfo)

worker.version_send(iserver,login,password,proxyUser,proxyPass,
  proxyServer,packageInfo)

File: worker.py:

def version_check(iserver,login,password,proxyUser,proxyPass,proxyServer,service):
    #code and more code

def version_get(iserver,login,password,proxyUser,proxyPass,proxyServer,service):
     #code and more code

def version_send(iserver,login,password,proxyUser,proxyPass,proxyServer,service):
    #code and more code

And now I have:

file caller.py:

import worker
args = (env, family, host, password, prefix, proxyServer,
        proxyUser, proxyPass, option, jokerVar
       )
worker.version_check(*args)
worker.version_get(*args)
worker.version_send(*args)

File: worker.py:

def version_check(*args):
  env = args[0]
  family = args[1]
  host = args[2]
  password = args[3]
  prefix = args[4]
  proxyServer = args[5]
  proxyUser = args[6]
  proxyPass = args[7]
  option = args[8]
  jokerVar = args[9]

  #code and more code

def version_get((*args):
  env = args[0]
  family = args[1]
  host = args[2]
  password = args[3]
  prefix = args[4]
  proxyServer = args[5]
  proxyUser = args[6]
  proxyPass = args[7]
  option = args[8]
  jokerVar = args[9]

  #code and more code

def version_send(*args):
  env = args[0]
  family = args[1]
  host = args[2]
  password = args[3]
  prefix = args[4]
  proxyServer = args[5]
  proxyUser = args[6]
  proxyPass = args[7]
  option = args[8]
  jokerVar = args[9]

  #code and more code

Using the old approach (actual code) I believe it is more "friendly" to call a function in one line only (as you can see on worker.py). But, using the new approach, I think the code get more extensive because for each function I have to define all the same variables. But is this the best practice? I'm still learning Python on a slow curve, so, sorry for any mistakes in the code.

And one important thing, most of the variables are retrieved from a database, so they are not stactic.

Answer 1

I really don't recommend defining functions like def version_check(*args): unless you specifically need to. Quick, without reading the source: what order are the arguments in? How do you specify a default value for proxyServer? Remember, "explicit is better than implicit".

The one time I routinely deviate from that rule is when I'm wrapping another function like:

def foo(bar):
    print 'Bar:', bar

def baz(qux, *args):
    print 'Qux:', qux
    foo(*args)

I'd never do it for such a simple example, but suppose foo is a function from a 3rd-party package outside my control with lots of defaults, keyword arguments, etc. In that case, I'd rather punt the argument parsing to Python than attempt it myself.

Personally, I'd write that as a class like:

class Worker(object):
    def __init__(iserver,login,password,proxyUser,proxyPass,proxyServer,service):
        self.iserver = iserver
        self.login = login
        self.password = password
        self.proxyUser = proxyUser
        self.proxyPass = proxyPass
        self.proxyServer = proxyServer
        self.service = service

    def version_check(self): ...

    def version_get(self): ...

    def version_send(self): ...

And then in the client, write:

from worker import Worker

w = Worker(iserver,login,password,proxyUser,proxyPass,proxyServer,service)
w.version_check()
w.version_get()
w.version_send()

If you really need to write functions with lots of arguments instead of encapsulating that state in a class - which is a more typically Pythonic way to do it - then consider the namedtuple datatype from recent Python versions. It lets you specify a tuple where items are addressable by keyword and can make for some very clean, elegant code.